1. Field of the Invention
The present invention relates to a detection device for passengers for judging a state of a passenger sitting on a seat of a vehicle, especially whether a child-seat is attached to the seat or not, according to output values of a plurality of load sensors.
2. Description of Related Art
Conventionally, as shown in FIG. 2, it is known a detection device for passengers which judges if a passenger sitting on a seat of a vehicle is an adult or a child or the seat is vacant, according to output values of load sensors 4A-4D disposed on supporting parts 3, . . . , 3 which support a seat 1.
Also, it is known detection devices for passengers which judge whether a child-seat 5 shown in FIG. 3 is attached to the seat 1 or not, and perform a control that does not deploy an airbag (not shown) to prevent the child-seat 5 from being impacted by a pressure of the airbag, when the child-seat 5 is attached (for reference, see Japan Patent Publication No. 2003-237535 and No. 2001-191830).
Further, all of the detection devices described in the two reference documents judge whether the child-seat 5 is attached or not according to a variation character of load detected after the child-seat 5 is attached.
However, when attaching the child-seat 5, a load such as a weight of the person who is attaching the child-seat 5, or a tightening force of a seat belt 6 (as shown in FIG. 3) for fastening the child-seat 5 and etc. may be applied to the child-seat 5 and detected by the plurality of the load sensors, therefore, erroneous judgments may be made according to the output values of the load sensors in the above-mentioned cases.